Publications by authors named "Witold A Jacak"

Metallic nanoparticles are frequently applied to enhance the efficiency of photovoltaic cells via the plasmonic effect, and they play this role due to the unusual ability of plasmons to transmit energy. The absorption and emission of plasmons, dual in the sense of quantum transitions, in metallic nanoparticles are especially high at the nanoscale of metal confinement, so these particles are almost perfect transmitters of incident photon energy. We show that these unusual properties of plasmons at the nanoscale are linked to the extreme deviation of plasmon oscillations from the conventional harmonic oscillations.

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Because of different mechanism of electro-signaling in myelinated axons than in dendrites or unmyelinated axons, the role of the myelin needs to be reconsidered upon new premises in distinction to conventional cable model. It occurs that the latter model is inapplicable for so-called saltatory conduction in myelinated axons and the former imagination on the role of the myelin based on the cable model is confusing. We show how the myelin sheath of axons controls the electro-signaling in myelinated neurons upon a wave-type ionic oscillation model of electro-signaling, ion plasmon-polariton model, in close agreement with observations of the saltatory conduction not reachable within traditional cable model approach.

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The application of metallic nanoparticles leads to an increase in the efficiency of solar cells due to the plasmonic effect. We explore various scenarios of the related mechanism in the case of metallized perovskite solar cells, which operate as hybrid chemical cells without p-n junctions, in contrast to conventional cells such as Si, CIGS or thin-layer semiconductor cells. The role of metallic nano-components in perovskite cells is different than in the case of p-n junction solar cells and, in addition, the large forbidden gap and a large effective masses of carriers in the perovskite require different parameters for the metallic nanoparticles than those used in p-n junction cells in order to obtain the increase in efficiency.

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We discuss a simple idealistic quantum entanglement based protocol for quantum random number generation allowing a trusted third party to publicly perform arbitrarily complex tests of randomness without any violation of the secrecy of the generated bit sequences. The protocol diminishes also an average time of the randomness testing (thus enabling arbitrary shortening of this time with increasing number of entangled qubits).

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We study strong optical coupling of metal nanoparticle arrays with dielectric substrates. Based on the Fermi Golden Rule, the particle-substrate coupling is derived in terms of the photon absorption probability assuming a local dipole field. An increase in photocurrent gain is achieved through the optical coupling.

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Plasmons are fundamental collective excitations in many particle charged systems like in free electron liquid in metals, high energy nuclear plasma in solar core or in fusion devices, in ion gas in ionosphere or in intra- and inter-galactic gas clouds. Plasmons play a central role also in small systems, in particular in metallic nanoparticles and in their arrays allowing for subdiffraction light manipulation. In analogy to metallic nanoparticles, we have developed description of the soft plasmonics in finite electrolyte systems confined in micrometer scale by insulating membranes.

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The propagation of collective wave type plasmonic excitations along infinite chains of metallic nanospheres has been analyzed, including near-, medium- and far-field contributions to the plasmon dipole interaction with all retardation effects taken into account. It is proven that there exist weakly-damped self-modes of plasmon-polaritons in the chain for which the propagation range is limited by relatively small Ohmic losses only. In this regime, the Lorentz friction irradiation losses on each nanosphere in the chain are ideally compensated by the energy income from the rest of the chain.

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An inclusion of the Lorentz friction to the damping of plasmons in metallic nanosphere is performed within the random phase approximation quasiclassical approach. The explanation of the experimentally observed anomalous red shift of plasmon resonance frequency with increase of the metallic particle radius for a large size limit is given and the perfect coincidence of the measured plasmon resonance red shift for Au nanospheres with radii 10 - 75 nm and the theory with accurately included Lorentz friction is demonstrated.

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In equidistant infinite chain of metallic nanospheres the collective mode of surface plasmons propagates without radiative losses, i.e., the Lorentz friction losses in each nanosphere are compensated by energy income in near-, medium- and far-field from the rest of the chain.

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The collective wave type plasmon polariton self-modes in the metallic (Au, Ag) nano-chain were determined and analyzed with respect to the nano-sphere size and chain separation parameters. At some regions for parameters, the undamped modes were identified when the interaction had been assumed as the near-field-zone dipole coupling. These modes were found on the rim of stability of the linear theory, which indicates artifact of the model of near-field coupling.

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